The present invention relates to a pothole protection mechanism for a vehicle including an aerial work platform (AWP).
Self-propelled AWPs such as scissor lifts are typically equipped with an apparatus that provides additional support for the lift in the event that a wheel is driven into a hole. Such an apparatus works normally by reducing the ground clearance to less than one inch when the platform of the AWP is elevated beyond a certain height.
One way of achieving this is by means of a bar or a plate that is attached to the chassis of the AWP and can be lowered down and locked in position when the platform is elevated. Subsequently, the bar or plate can be raised up when the platform is lowered.
The mechanism that performs the lowering, locking and raising tasks is referred to as a pothole protection mechanism. Important requirements of the pothole protection mechanism are to avoid any crushing hazard while deploying the bar and to be able to tolerate fixed objects on the ground while raising the bar.
Current designs are typically based on one of two concepts. A typical six-bar mechanism and a spring are provided to ensure the locking position. This design, however, suffers from excessive numbers of parts and consequently from cost and reliability. A typical four-bar mechanism incorporates a linear actuator linking two of its links. The actuator is either hydraulic or electrical. Drawbacks of this design, however, include reliability, and potential leakage of hydraulic fluid.